Speedmasters

Had one on the dyno recently....... 421” SBC.
Very nice rotating assy, but the pistons were way way down the hole.
I can’t remember what the cam was, but I seem to recall it was pretty lumpy(I’ll see if I can find the specs), but it had unported open chamber smogger heads(882’s), rpm intake...... 375hp, and all done before 5k.
Customer wanted to get a number on it before taking it apart for some upgrades.
Edit- the intake was a split single plane Holley SD, the one with the runner connecting cyls #7 & #8 together.
Cam was XE274.

My feelings about the SM headed 360 are that the zero planning resulted in a rather poor piston choice , which I think was the biggest “issue” with that overall build.
We didn’t build the short block, so who knows if it was set up with performance clearances, or stock rebuild type clearances.
It may have had piston to wall clearances that were costing a few hp.

I feel like the “same basic” combo, but with a better piston/CR/quench combo, done with performance in mind could have yielded 30-40 more HP(to get it into the 1hp/ci range), and then swapping out the hyd cam for a small solid would up it another 20-30hp, if for no other reason than the lifters wouldn’t be acting up, which would allow the curve to hang on longer.